1. Technical Field
The present invention relates to a length measuring instrument.
2. Background Information
One such length measuring instrument is described for instance in European Patent Disclosure 0 418 212 A2. Such length measuring instruments are known as encapsulated length measuring instruments, and they serve to measure the position of two objects that are displaceable relative to one another. Encapsulated length measuring instruments are used especially in machining machines for measuring the relative motion of a tool relative to a workpiece that is to be machined.
The length measuring instrument known from European Patent Disclosure 0 418 212 A2 includes a hollow profile section, which protects a scale secured inside it from environmental factors. The face ends of the hollow profile section are each closed with an end piece, which is also embodied for mounting the hollow profile section on one of the objects to be measured. The end piece has an insert part, with which it plunges into the inside of the opening in the hollow profile section. A seal disposed on the end piece effects sealing between the end piece and the hollow profile section. For receiving the seal, there is a groove in the insert part.
Instead of a seal acting along the circumference, the concept of a butt seal is also employed in length measuring instruments. One example is found in German Patent Disclosure DE 34 12 879 A1. There, the face end of a hollow profile section that has a scale is closed by an end piece, and a seal is inserted between the face end of the hollow profile section and the end piece placed onto it.